This invention relates to the protection of cells, usually anaerobic microorganisms. There are a number of situations where the retention of viability of anaerobic microorganisms is important. One such situation is in diagnostic assays for determining the presence of a pathogenic microorganism. In such assays it is important that the anaerobic microorganism remain viable between the period beginning with the collection of a specimen from a patient and ending with the diagnostic assay being conducted on the specimen. Loss of viability of the microorganism will result in a false test with obvious consequences.
The transport and culture of anaerobic microorganisms requires the use of a system that prevents the microorganism from being killed by exposure to oxygen. In one approach air containing oxygen is substituted by oxygen-free nitrogen or carbon dioxide, Special media are conventionally employed. Other approaches employ media containing ingredients such as sodium thioglycollate, cysteine, sodium sulfide, sodium dithionite, ascorbic acid and the like that chemically combine with dissolved oxygen to deplete the oxygen content of the culture medium. For routine procedures for maintaining anaerobic microorganisms, microbiologists use reducing media stored in ordinary tightly capped test tubes. Other systems employed to reduce oxygen in working with cultures of anaerobic microorganisms, particularly with petri plates, involve packets of chemicals, e.g., sodium bicarbonate, sodium borohydride, and palladium, contained in a sealed container. The palladium serves as a catalyst to cause the oxygen to react with hydrogen produced by hydrolysis of the borohydride to produce water.
2. Description of the Related Art
Oxygen and the metabolism of Peptostreptococcus anaerobius UPI 4330-1 is discussed by Hoshino, et al., Journal of General Microbiology (1978) 107:235-248. Oxygen and the growth and metabolism of Clostridium acetobutylicum is disclosed by O'Brien, et al. Journal of General Microbiology (1971) 68: 307-318. Oxygen scavenging with enzymes is described in U.S. Pat. No. 4,414,334. The bactericidal effect of cysteine exposed to atmospheric oxygen is described by Carlsson, et al., Applied and Environmental Microbiology (1979) 37: 383-390. Immobilized glucose oxidase and its use for oxygen removal from beer is described by Hartmeier et al., MBAA Technical Quarterly (1981) 18: 145-149. Basic trials or possible industrial applications of an immobilized glucose oxidase-catalase system is disclosed by Hartmeier in Biotechnol. Lett. (1979) 1:21-26. Deoxygenation of protective coating compositions, e.g., paints, the compositions, and their use are disclosed in Eur. Pat. Appl. EP55240A1. The possibility that endogenous catalase and/or peroxidase protects certain anaerobes against oxygen is discussed by Morris, J. Appl. Bacterial. (1976) 40:229-244.